There is a problem nowadays in the way of improving efficiency, lowering metal weight and improving reliability and output of mass-exchange towers and gas-liquid separators.
As mass-exchange towers and gas-liquid separators are basic apparatuses used in processes of preparation and processing of gas, bringing a solution to this problem would open the way to providing compact gas processing and separation plants for gas condensate continental shelf deposits and polar regions where low weight, small size and high capacity-to-mass ratio equipment is especially appreciated.
Known in the art is a multiple-vane axial swirl device for separating phases, comprising a coaxial pipe extending through a bunch of solid inclined vanes for gas recirculation in a circuit "deposition zone - reduced pressure zone" in the central area of the tail part of the swirl device (cg. USSR Inventor's Certificate No. 436677, Int.Cl. B 04 C 3/06, publ 25.07.1974).
This swirl device has a large axial size because of an unwieldy recirculation system.
Also known in the art is an axial swirl device for a contact and separation member having vanes with through radial passages (cf. USSR Inventor's Certificate No. 203622, Int.Cl. B 01 d, publ. 9.10.1967). A deflector in the form of a converging tube is provided above, and adjacent to the swirl device for restricting the swirled gas and liquid flow passing therethrough.
This construction allows processes of heat- and mass-exchange and phase separation in gas-liquid systems to be intensified.
However, the converging tube restriction of swirled flow results in increased energy consumption for forcing the flow through while lowering throughput capacity since flow velocity at the outlet edge of the converging tube is limited to a certain value so as to comply with conditions for ensuring reliable separation of contacted gas and liquid phases.
Known in the art is an axial swirl device for centrifugal separation of phases of a gas and liquid mixture (cf. U.S. Pat. No. 3,693,229, Int.Cl. B 01 d 45/12). The swirl device comprises a bunch of inclined vanes secured to a central sleeve, and for recirculation of gas being separated, use is made of a reduced pressure zone created axially along the sleeve of the swirl device, the gas being sucked into the sleeve through passages of individual vanes (hollow vanes). The vane passages may, in certain applications, extend tangentially to the interior of the central sleeve. The sleeve proper has a cigar-like extension downstream the outlet edge of the vanes, with a gradual narrowing of its outer surface through a decrease in the wall thickness to fit the dimensions of the open cylindrical cavity.
This construction of the axial swirl device makes it possible to increase throughput capacity of a contact and separation member in terms of gas as compared with the abovedescribed swirl devices.
However, throughput capacity in terms of liquid remains low in this prior art device because of a weak swirling of liquid drops that break through together with recirculated gas. This weak swirling calls for a considerable distance at which the tail cigar-like portion of the swirl device should be spaced from a separation unit so as to remove the separated liquid film.
In addition, the cigar-like extension of the sleeve of the swirl device enables individual drops passing along its surface to separate at a small distance from the central axis of the swirl device where swirling of the flow is rather ineffectual for reliable separation of phases with substantial liquid flow rates.
Liquid may be accumulate in the interior of the sleeve when the prior art apparatus operation is suspended so that additional amounts of heating steam and hot water are required for removing the liquid during inspection and repairs of the apparatus.
The abovementioned disadvantages of the prior art swirl device impose a preferably horizontal working position, thus restricting the field of application since vertical position of a swirl device is generally desirable in mass-exchange apparatuses.